Key Facts

Overview

Eunomia is a very large asteroid circling the sun between Mars and Jupiter, inside the main asteroid belt. NASA JPL does not treat Eunomia as potentially hazardous, because its orbit never carries it near Earth.

One lap around the sun takes Eunomia 1,570 days (4.3 years). Over that circuit it swings between 2.15 AU and 3.14 AU from the sun, travelling at an average of 18.31 km/s. At 231.7 kilometers across, Eunomia is bigger than 99% of known asteroids — roughly the size of the U.S. state of Maryland.

Eunomia has been watched long enough to time its spin: one full turn on its axis takes 6.08 hours.

Eunomia is classed as S on the Tholen scale, S on SMASSII.

No Close Approaches

At their nearest, the orbits of Eunomia and Earth stay 1.19 AU apart. That is a comfortable margin, and it holds at every point in the orbit.

Orbital simulations run by NASA JPL's CNEOS turn up no close approaches to Earth.

Images and Observations

The orbit of Eunomia is pinned down by sightings going back to Sept. 2, 1851, the most recent officially logged on June 2, 2023. The IAU Minor Planet Center holds 4,747 observations behind that solution.

Accessibility and Exploration

The NHATS study does not rate Eunomia as a realistic destination for a crewed mission.

Similar Objects

These objects follow orbits with much the same shape and tilt as Eunomia:

References

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Orbital Elements

  • Epoch: 2460200.5 JD
  • Semi-major axis: 2.643 AU
  • Eccentricity: 0.1871
  • Inclination: 11.75°
  • Longitude of Ascending Node: 292.91°
  • Argument of Periapsis: 98.76°
  • Mean Anomaly: 289.99°

Physical Characteristics

  • Diameter: 231.68900 km
  • Magnitude: 5.41
  • Albedo: 0.248
  • Spectral type (Tholen): S
  • Spectral type (SMASS): S

Derived Characteristics

  • Orbit Period: 1,570 days (4.3 years)
  • Avg. Orbit Speed: 18.31 km/s
  • Aphelion Distance: 3.14 AU
  • Perihelion Distance: 2.15 AU
  • Rotation Period: 6.08 hours

Map Comparison

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Orbit Simulation

Sky Map

A ◯ pink circle marks where Eunomia sits. It may fall outside your current field of view — use the controls below to change the position, location and time.